Substitution and Migratory Insertion Reactions of Square-Planar

3782

Organometallics 2001, 20, 3782-3794

Substitution and Migratory Insertion Reactions of Square-Planar Allenylidene Iridium Complexes† Kerstin Ilg and Helmut Werner* Institut fu¨ r Anorganische Chemie der Universita¨ t Wu¨ rzburg, Am Hubland, D-97074 Wu¨ rzburg, Germany Received April 30, 2001

A series of (allenylidene)iridium(I) complexes of general composition trans-[IrX{dCdCd C(Ph)R}(PiPr3)2] [X ) Br (5), I (6), NCO (7, 8), NCS (9, 10), OH (11, 12), N3 (13, 14)] was prepared from the corresponding chloro derivatives trans-[IrCl{dCdCdC(Ph)R}(PiPr3)2] (3, 4) by salt metathesis. An X-ray crystal structure analysis of 4 (R ) Ph) confirmed the almost linear arrangement of the Ir-C-C-C chain. The azido compounds 13 (R ) Ph) and 14 (R ) tBu) react with CO by migratory insertion of the allenylidene ligand into the Ir-N3 bond. While the product trans-[Ir{C≡C-CR(Ph)N3}(CO)(PiPr3)2] with R ) tBu (16) is thermally stable, the related complex with R ) Ph (15) rearranges slowly in benzene to the metalated acrylonitrile derivative trans-[Ir{C(CN)dCPh2}(CO)(PiPr3)2] (17) by elimination of N2. Treatment of the phenolato compound trans-[Ir(OPh){dCdCdC(Ph)tBu}(PiPr3)2] (19), obtained from the analogous hydroxo derivative 12 and phenol, with CO also proceeds by migratory insertion and affords the functionalized (alkynyl)iridium(I) complex trans-[Ir{Ct C-CtBu(Ph)OPh}(CO)(PiPr3)2] (20) in excellent yield. The Lewis basicity of the hydroxo compounds 11 and 12 was also illustrated by the reactions with CF3CO2H, NEt3‚3HF, and [pyH]BF4, which gave the substitution products trans-[Ir(κ1-O2CCF3){dCdCdC(Ph)tBu}(PiPr3)2] (21), trans-[IrF(dCdCdCPh2)(PiPr3)2] (22), and trans-[Ir{dCdCdC(Ph)tBu}(py)(PiPr3)2]BF4 (23), respectively. In methanol solution, both 11 and 12 react by complete fragmentation of 1 equiv of CH3OH to afford the octahedral (allenyl)dihydridoiridium(III) complexes [IrH2{CHdCdC(Ph)R}(CO)(PiPr3)2] (24, 25). An unprecedented type of insertion reaction occurs by treating the hydroxo derivatives 11 and 12 with an excess of 1-alkynes R′CtCH (R′ ) Ph, CO2Me), which leads to the formation of the novel five-coordinate iridium(III) compounds [Ir(CtCR′)2{η1-(E)-CHdCR′-CHdCdC(Ph)R}(PiPr3)2] (26-29). From 26, 27 (R′ ) Ph), and CO, the octahedral 1:1 adducts 30 and 31 are formed. The molecular structures of 22 and 26 have been determined by X-ray crystallography. Introduction In the search for analogues of the square-planar rhodium complexes trans-[RhCl(dCdCdCRR′)(PiPr3)2],1 we recently reported that the iridium counterpart trans[IrCl(dCdCdCPh2)(PiPr3)2] can be obtained from the dihydrido compound [IrH2Cl(PiPr3)2] and HCtCCPh2OH via [IrHCl(CtCCPh2OH)(PiPr3)2] or the isomer trans-[IrCl(dCdCHCPh2OH)(PiPr3)2] as the intermediate.2 Since allenylidenes such as vinylidenes and the more carbon-rich cumulenylidenes C(dC)ndCRR′ (n ) 2, 3)3 are predicted to be good π-acceptor ligands,4 it could be anticipated that in square-planar (allenylidene)iridium(I) complexes of the general composition † Dedicated to Professor R. G. Bergman on the occasion of his 60th birthday. (1) (a) Werner, H.; Rappert, T. Chem. Ber. 1993, 126, 669-678. (b) Werner, H.; Rappert, T.; Wiedemann, R.; Wolf, J.; Mahr, N. Organometallics 1994, 13, 2721-2727. (2) Werner, H.; Lass, R. W.; Gevert, O.; Wolf, J. Organometallics 1997, 16, 4077-4088. (3) For iridium complexes with carbon-rich cumulenylidenes as ligands see: (a) Lass, R. W.; Steinert, P.; Wolf, J.; Werner, H. Chem. Eur. J. 1996, 2, 19-23. (b) Ilg, K.; Werner, H. Angew. Chem. 2000, 112, 1691-1693; Angew. Chem., Int. Ed. 2000, 39, 1632-1634. (4) Schilling, B. E. R.; Hoffmann, R.; Lichtenberger, D. L. J. Am. Chem. Soc. 1979, 101, 585-591.

trans-[IrCl(dCdCdCRR′)(PiPr3)2] the C3RR′ unit would exert a strong influence on the ligand in the trans position. Hence, we started to study the substitution reactions of the chloro derivatives with the particular aim to replace the chloride not only by other halides but also by pseudohalides such as OCN- or N3- and by hydroxide. It was only recently that we observed that the vinylidene iridium(I) compounds trans-[IrX(dCd CRR′)(PiPr3)2] with X ) OH and N3 are useful starting materials for the synthesis of a variety of iridium(I) complexes which are not (or hardly) accessible on other routes.5 In this paper we describe our investigations on the reactivity of iridium allenylidenes trans-[IrCl{dCdCd C(Ph)R}(PiPr3)2] toward various anionic nucleophiles. Moreover, we illustrate that in the presence of CO the C3RR′ unit undergoes migratory insertion reactions into both Ir-N and Ir-O bonds, thus generating new functionalized alkynyl groups coordinated to iridium(I). A rather unusual insertion process takes place upon treatment of the hydroxo complexes trans-[Ir(OH){dCd CdC(Ph)R}(PiPr3)2] with terminal alkynes, which leads (5) Werner, H.; Ilg, K.; Weberndo¨rfer, B. Organometallics 2000, 19, 3145-3153.

10.1021/om010353m CCC: $20.00 © 2001 American Chemical Society Publication on Web 07/27/2001

Square-Planar Allenylidene Ir Complexes

Organometallics, Vol. 20, No. 17, 2001 3783

Table 1. Crystallographic Data for 4, 22, and 26 formula fw cryst size, mm3 cryst syst space group cell dimens determn a, Å b, Å c, Å R, deg β, deg γ, deg V, Å3 Z dcalc, g‚cm-3 temp, K µ, mm-1 scan method 2θ(max), deg tot. no. of reflns no. of unique reflns no. of obsd reflns [I > 2σ(I)] no. of reflns used for refinement no. of params refined final R indices [I > 2σ(I)] R indices (all data) absolute structure param resid electron density, e Å-3 a

w-1

[Fo2 +

) 1/[σ2Fo2 2Fc2]/3.

+

(0.0636P)2

C33H52ClIrP2 738.34 0.19 × 0.16 × 0.15 monoclinic P21 (No. 5) 25 reflns, 10° < θ < 15° 11.9916(10) 11.1053(10) 12.7777(10)

C33H52FIrP2 721.89 0.19 × 0.14 × 0.11 monoclinic P21/n (No. 14) 24 reflns,5° < θ < 15° 8.6057(13) 34.735(3) 10.8860(15)

98.658(10)

95.737

1682.2(2) 2 1.458 193(2) 4.162 ω/θ 46 3704 3534 [R(int) ) 0.0404] 3338

3237.7(7) 4 1.481 173(2) 4.248 ω/θ 47 5131 4604 [R(int) ) 0.0657] 2743

C57H69IrP2 1008.26 0.21 × 0.18 × 0.16 triclinic P1 h (No. 2) 24 reflns,5° < θ < 15° 13.600(4) 13.634(4) 14.994(4) 83.92(2) 66.63(3) 87.23(2) 2537.8(13) 2 1.319 193(2) 2.728 ω/θ 45 6946 6598 [R(int) ) 0.0483] 5794

3534 347 R1 ) 0.0332, wR2 ) 0.0833a R1 ) 0.0368, wR2 ) 0.0866a 0.317(14) 0.624/-0.712

4597 346 R1 ) 0.0661, wR2 ) 0.1386a R1 ) 0.1363, wR2 ) 0.1702a

6598 598 R1 ) 0.0370 wR2 ) 0.0672a R1 ) 0.0464, wR2 ) 0.0718a

+ 0.0000P] (4),

1/[σ2Fo2

+

(0.0750P)2

Scheme 1

to the formation of a highly unsaturated C5 ligand. A few of these results have already been communicated.6 Results and Discussion Preparation of Allenylidene Iridium Complexes by Salt Metathesis. In addition to the previously described chloro compound trans-[IrCl(dCdCdCPh2)(PiPr3)2] (4),2 the structurally related complex 3, containing one phenyl and one tert-butyl group as substituents at the γ-carbon atom of the IrC3 chain, was also prepared (Scheme 1). The procedure to obtain 3 followed the methodology that we had developed for the diphenyl analogue 4. Treatment of the dihydrido complex 1 with the propargylic alcohol HCtCCPh(tBu)OH in hexane at -20 °C led to the formation of the iridium(III) derivative 2, which was isolated as a red solid in 84% (6) Ilg, K.; Werner, H. Organometallics 1999, 18, 5426-5428.

1.173/-1.682 + 0.0000P] (22),

1/[σ2Fo2

0.620/-1.097 +

(0.0160P)2

+ 5.7281P] (26), where P )

yield. Typical features of 2 are the hydride resonance at δ -42.44 (i.e., at remarkably high field) in the 1H NMR spectrum and the OH, Ir-H, and C≡C stretching modes at, respectively, 3481, 2300, and 2092 cm-1 in the IR spectrum. Similar data have been observed for related five-coordinate hydrido(alkynyl)- and hydrido(diyndiyl)iridium(III) complexes.2 Since only one signal appears in the 31P NMR spectrum of 2, we conclude that the two phosphine ligands are trans disposed in the basal plane of a square pyramid. If a solution of 2 in ether is stirred for 3 h at room temperature in the presence of small amounts of trifluoroacetic acid, a quantitative conversion to the allenylidene compound 3 occurs by elimination of water. The IR and NMR spectroscopic data of 3 (which is a redviolet, only moderately air-sensitive solid) are similar to those of 4 and of the analogous rhodium(I) complex trans-[RhCl{dCdCdC(Ph)tBu}(PiPr3)2].7 Since in each of the 1H, 13C, and 31P NMR spectra of 4 only one set of signals for the phosphorus, hydrogen, and carbon atoms of the PiPr3 ligands has been observed, we assume that the barrier for rotation around the Ir-C bond is quite small on the NMR time scale. Attempts to replace the chloro ligand of 3 or 4 by methyl, vinyl, or phenyl using the corresponding organo lithium compound as a substrate failed. If instead of RLi the analogous Grignard reagent RMgX (X ) Br or I) reacted with the chloro derivative, a mixture of products was formed, among which the bromo or iodo complexes trans-[IrX{dCdCdC(Ph)R}(PiPr3)2] (X ) Br, I) were the major components. These compounds (illustrated by using 4 as the starting material) are more conveniently prepared by salt metathesis from the (7) Laubender, M.; Werner, H. Chem. Eur. J. 1999, 5, 2937-2946.

3784

Organometallics, Vol. 20, No. 17, 2001

Ilg and Werner Scheme 2

chloro complex and NaBr or KI, respectively. Both 5 and 6 (see Scheme 2) are deeply colored solids which have been characterized by elemental analyses and IR and NMR spectroscopy. In solution, 5 and even more 6 are less stable than 4, which is probably due to the weakening of the allenylidene-metal bond by reducing the π-donor capability of the ligand X in trans disposition. Compounds 3 and 4 react not only with alkalimetal halides but also with excess NaOCN and KSCN in acetone at room temperature to give the isocyanato and isothiocyanato complexes 7-10 as red or dark red, almost air-stable solids in 86-95% isolated yield. The IR spectra of 7 and 8 display two strong absorptions at around 2230 and 1450 cm-1, which are assigned to the asymmetrical and symmetrical NCO stretching modes. Since it has been established that the symmetrical stretch for O-bonded isocyanates appears below 1200 cm-1 and that for N-bonded NCO ligands in the region between 1300 and 1500 cm-1,8 we conclude that in 7 and 8 an Ir-NCO linkage exists. A similar criterion can be applied regarding the coordination of the NCS ligand in compounds 9 and 10. Since for S-bonded isothiocyanates the asymmetrical NCS stretching mode should be observed at around 2120 cm-1 and for the N-bonded analogues at around 2070 cm-1,9 the appearance of an infrared band at 2077 cm-1 for 9 and at 2080 cm-1 for 10 indicates that in both cases the isothiocyanate is linked via the nitrogen atom to iridium(I). In this context we note that the IR spectrum of the Vaska-type complex trans-[Ir(NCS)(CO)(PPh3)2] also indicates an N-coordination of the NCS unit.10 In contrast to the hydroxorhodium(I) compounds trans-[Rh(OH)(dCdCdCRR′)(PiPr3)2], which were pre(8) (a) Burmeister, J. L.; Deardorff, E. A.; Jensen, A.; Christiansen, V. H. Inorg. Chem. 1970, 9, 58-63. (b) Mu¨ller, U. Z. Anorg. Allg. Chem. 1973, 396, 187-198. (9) (a) Jurisson, S.; Halihan, M. M.; Lydon, J. D.; Barnes, C. L.; Nowotnik, D. P.; Nunn, A. D. Inorg. Chem. 1998, 37, 1922-1928. (b) Nakamoto, K. Infrared and Raman Spectra of Inorganic and Coordination Compounds, Part B; Wiley: New York, 1997. (10) DeStefano, N. J.; Burmeister, J. L. Inorg. Chem. 1971, 10, 9981003.

pared by treatment of the corresponding chloro derivatives with KOtBu in a mixture of benzene and tert-butyl alcohol,11 the iridium(I) counterparts 11 and 12 (Scheme 2) were obtained from 3 or 4 and excess KOH in acetone as orange and green microcrystalline solids. The presence of the hydroxo ligand is indicated both by the strong absorption at 3643 cm-1 (11) or 3648 cm-1 (12) in the IR and by the broadened singlet at δ 4.25 (11) or 3.80 (12) in the 1H NMR spectrum. The chemical shifts for the resonances of the allenylidene carbon atoms in the 13C NMR spectrum of 12 are quite similar to those of 3, which supports the assumption that the trans influence of the chloro and the hydroxo ligands is of comparable magnitude. The synthesis of the azido complexes 13 and 14 follows the route that we have used to obtain the isocyanato and isothiocyanato analogues 7-10. This procedure is equally similar to that for the preparation of the rhodium(I) compounds trans-[RhN3(dCdCdCRR′)(PiPr3)2],7 trans-[RhN3(CO)(PR3)2] (R ) Ph, Cy),12 and [RhN3(PPh3)3].13 The most typical spectroscopic data of 13 and 14 are the two low-field signals (both triplets) in the 13C NMR spectra between δ 250 and 205 for the R- and β-carbon atoms of the IrC3 chain and the intense ν(N3) mode in the IR spectra at 2066 cm-1 (13) and 2078 cm-1 (14), respectively. Migratory Insertions of Allenylidene Units into Ir-N and Ir-O Bonds. In acetone, the azido complexes 13 and 14 react quite rapidly with carbon monoxide to afford yellow microcrystalline solids 15 and 16 in 83% and 90% isolated yield. The analytical composition of both 15 and 16 corresponds to that of 1:1 adducts between the corresponding starting material and CO. While in the IR spectra of the products two (11) Werner, H.; Wiedemann, R.; Laubender, M.; Windmu¨ller, B.; Wolf, J. Chem. Eur. J. 2001, 7, 1959-1967. (12) (a) Vaska, L.; Peone, J. Chem. Commun. 1971, 418-419. (b) van Gaal, H. L. M.; van den Bekerom, F. L. A. J. Organomet. Chem. 1977, 134, 237-248. (13) Beck, W.; Fehlhammer, W. P.; Po¨llmann, P.; Scha¨chl, H. Chem. Ber. 1969, 102, 1976-1987.


Organometallics, Vol. 20, No. 17, 2001 3785 Scheme 3

Scheme 4

strong absorptions at, respectively, 2098 and 1933 cm-1 for 15 and 2104 and 1932 cm-1 for 16 are observed, assigned to N3 and CO stretching modes, the 13C NMR spectra exhibit a triplet resonance at around δ 125127 and a singlet resonance at around δ 115 for the carbon atoms of an alkynyl group. From these data we conclude (see Scheme 3) that treatment of the azido complexes with CO results in a migration of the N3ligand to the allenylidene unit and that the intact azido group is linked to the γ-carbon atom of the C3 chain. The thermal stability of compounds 15 and 16 is remarkably different. While solutions of 16 in benzene can be stirred for 24 h at room temperature without any decomposition or rearrangement, the corresponding diphenyl derivative 15 is more labile and, under the same conditions, slowly reacts to give first an (nonisolated) intermediate and then a new product. According to the IR spectra, taken after 4-6 h, the intermediate contains besides the carbonyl ligand [ν(CO) ) 1909 cm-1] an azido group [ν(N3) ) 2076 cm-1] and a cumulene fragment [ν(CdCdC) ) 1862 cm-1]. We therefore assume that in the first step of the thermal reaction of 15 the allenyl complex trans-[Ir{C(N3)dCd CPh2}(CO)(PiPr3)2] is generated by migration of the N3 unit from the γ-carbon to the R-carbon atom of the C3 chain. Stirring the benzene solution for 24 h leads to

the disappearance of the IR bands of the intermediate and, after evaporation of the solvent and recrystallization from acetone at -78 °C, to the isolation of a yellow solid with the analytical composition of 17 in 90% yield. The IR spectrum of 17 displays instead of three (as for the intermediate) two strong absorptions at 2159 and 1937 cm-1, which we assign to CN and CO stretching modes. Since the 13C NMR spectrum exhibits three resonances in the region between δ 161 and 126, which all show P,C couplings, we assume that the new product is a four-coordinate carbonyl(vinyl)iridium(I) derivative. We note that a related rhodium(I) complex (with panisyl instead of phenyl substituents at the β-carbon atom of the vinylic ligand) is known and has been characterized by X-ray crystallography.7 In the presence of CO, the phenolato compound 19 behaves similarly to the azido analogue 14. For the preparation of both 18 and 19, instead of a salt metathesis of the chloro derivatives 3, 4, and NaOR14 the more convenient method consists in the acid-base reaction of 11 and 12 with phenol (Scheme 4). The reactions are carried out in benzene at room temperature and afford the phenolates 18 and 19 as dark red or brown solids in excellent yield. Under the conditions used for the synthesis, there is no attack of PhOH at the allenylidene unit. The reaction of 1915 with CO takes

3786


Ilg and Werner Scheme 5

place in pentane and gives the insertion product 20 as a yellow, moderately air-sensitive solid in 83% yield. The presence of the functionalized alkynyl ligand is indicated in the 13C NMR spectrum by the appearance of two signals at δ 125.4 (triplet for CR) and 115.2 (singlet for Cβ). Moreover, the elemental analysis and the mass spectrum confirm the supposed composition. The (trifluoroacetato)iridium(I) complex 21, prepared from the hydroxo compound 12 and CF3CO2H in benzene, also reacts with CO, but, in contrast to the analogous reaction of 12 with phenol, in this case no analytically pure product could be isolated. Reactions of the (Allenylidene)hydroxo Iridium Complexes with Other Acidic Substrates. The ability of the hydroxo compounds 11 and 12 to behave as organometallic Bro¨nsted bases is illustrated not only by the reactions with PhOH and CF3CO2H but also by those with NEt3‚3HF and [pyH]BF4 (see Scheme 5). We have recently shown that triethylamine-tris(hydrogen fluoride), which has been used for the first time by Grushin et al. as a versatile fluorinating agent in the chemistry of late transition metals,16 can be successfully applied for the preparation of rhodium(I) as well as iridium(I) complexes with metal-fluorine bonds.5,17 Treatment of 11 with NEt3‚3HF in benzene affords, after recrystallization from acetone, the fluoro compound 22 as a red solid in 88% yield. The single (14) Formation of alkoxo and aroxo metal compounds from chloro derivatives by salt metathesis is known; see: (a) Gregorio, G.; Pregaglia, G.; Ugo, R. Inorg. Chim. Acta 1969, 3, 89-93. (b) Vaska, L.; Peone, J. J. Chem. Soc. D 1971, 418-421. (c) Rees, W. M.; Atwood, J. D. Organometallics 1985, 4, 402-404. (d) Rees, W. M.; Churchill, M. R.; Fettinger, J. C.; Atwood, J. D. Organometallics 1985, 4, 21792185. (e) Churchill, M. R.; Fettinger, J. C.; Rees, W. M.; Atwood, J. D. J. Organomet. Chem. 1986, 308, 361-371. (15) Compound 18 behaves similarly toward CO, but this reaction has not been studied in detail. (16) (a) Fraser, S. L.; Antipin, M. Y.; Khroustalyov, V. N.; Grushin, V. V. J. Am. Chem. Soc. 1997, 119, 4769-4770. (b) Pilon, M. C.; Grushin, V. V. Organometallics 1998, 17, 1774-1781. (17) Gil-Rubio, J.; Weberndo¨rfer, B.; Werner, H. J. Chem. Soc., Dalton Trans. 1999, 1437-1444.

Figure 1. Molecular diagram of compound 4. Selected bond distances (Å) and angles (deg): Ir-Cl ) 2.3649(19), Ir-P1 ) 2.344(3), Ir-P2 ) 2.340(3), Ir-C1 ) 1.862(7), C1C2 ) 1.247(11), C2-C3 ) 1.360(11); Cl-Ir-P1 ) 89.55(15), Cl-Ir-P2 ) 89.27(15), Cl-Ir-C1 ) 178.1(5), P1-IrP2 ) 178.42(9), P1-Ir-C1 ) 90.6(6), P2-Ir-C1 ) 90.5(6), Ir-C1-C2 ) 178.5(14), C1-C2-C3 ) 176.7(14).

resonances in the 19F and 31P NMR spectra of 22 are split into a triplet and a doublet, both due to P,F couplings. The molecular structure of 22 and, for comparison, also that of the chloro analogue 4 has been determined by X-ray crystallography. The molecular diagrams in Figures 1 and 2 reveal that in both cases the iridium is coordinated in an almost perfect square-planar fashion. The two phosphine ligands are trans to each other with an eclipsed conformation along the P-Ir-P axis. The Ir-C1 distance of 1.85(2) Å for 4 and 1.862(7) Å for 22 is slightly shorter than in the carbene complex trans[IrCl(dCPh2)(PiPr3)2] (1.887(5) Å)18 but somewhat longer than in the corresponding vinylidene derivative trans-


Figure 2. Molecular diagram of compound 22. Selected bond distances (Å) and angles (deg): Ir-F ) 2.015(10), IrP1 ) 2.317(4), Ir-P2 ) 2.326(4), Ir-C1 ) 1.85(2), C1-C2 ) 1.22(2), C2-C3 ) 1.37(2); F-Ir-P1 ) 88.5(3), F-Ir-P2 ) 89.0(3), F-Ir-C1 ) 179.3(6), P1-Ir-P2 ) 177.51(16), P1-Ir-C1 ) 91.0(5), P2-Ir-C1 ) 91.5(5), Ir-C1-C2 ) 177.1(17), C1-C2-C3 ) 173(2).

Figure 3. Molecular diagram of compound 26. Selected bond distances (Å) and angles (deg): Ir-C1 ) 1.998(6), IrC40 ) 2.020(6), Ir-C50 ) 2.018(6), Ir-P1 ) 2.359(2), IrP2 ) 2.371(2), C1-C2 ) 1.35(1), C2-C3 ) 1.46(1), C3C4 ) 1.32(1), C4-C5 ) 1.31(1); C1-Ir-C40 ) 98.0(2), C1Ir-C50 ) 89.5(2), C1-Ir-P1 ) 95.1(2), C1-Ir-P2 ) 96.7(2), C40-Ir-C50 ) 172.4(3), C40-Ir-P1 ) 92.2(2), C40-Ir-P2 ) 89.3(2), C50-Ir-P1 ) 87.7(2), C50-Ir-P2 ) 89.3(2), P1-Ir-P2 ) 167.77(6), Ir-C1-C2 ) 135.8(5), C1-C2-C3 ) 125.0(6), C2-C3-C4 ) 127.9(6), C3-C4C5 ) 175.1(6), Ir-C40-C41 ) 176.9(5), Ir-C50-C51 ) 177.9(6).

[IrCl(dCdCHCO2Me)(PiPr3)2] (1.764(6) Å).19 This order of bond lengths is in agreement with that found in the chloro rhodium counterparts. The two carbon-carbon distances in the IrC3 chain differ by 0.12-0.15 Å, which indicates that besides the usual bonding description Ird (18) Ortmann, D. A.; Weberndo¨rfer, B.; Scho¨neboom, J.; Werner, H. Organometallics 1999, 18, 952-954. (19) Werner, H.; Ho¨hn, A.; Schulz, M. J. Chem. Soc., Dalton Trans. 1991, 777-781.


CdCdC a second zwitterionic resonance structure has to be taken into consideration.20 The IrC3 chain is nearly linear with only a slight bending at C2 in the case of 22. We note that the ipso-carbon atoms C30 and C40 of the two phenyl groups do not lie in the same plane as the ligand atoms around iridium, the dihedral angle between the best planes [X-Ir-C1-P1-P2] and [C3C30-C40] being 14(1)° for 4 and 19(2)° for 22, respectively. There is a small difference in the Ir-P bond distances in 4 and 22, which we explain by the different electronic influence of the chloro and fluoro ligands. Under acidic conditions, the OH group of the Bro¨nsted bases trans-[Ir(OH){dCdCdC(Ph)R}(PiPr3)2] can also be replaced by neutral ligands. This is exemplified by the preparation of the cationic complex 23 from 12 and [pyH]BF4 (see Scheme 5). The composition of 23, which was isolated as a red-violet, thermally rather labile solid, was substantiated not only by elemental analysis but also by conductivity measurements and spectroscopic data. The 13C NMR spectrum of 23 exhibits, in contrast to the spectra 4 and 22, the resonance of the R-carbon atom of the IrC3 unit at significantly lower field than that of the β-carbon atom. The acetone derivative trans-[Ir(OdCMe2){dCdCdC(Ph)tBu} (PiPr3)2]BF4 seems to be more labile than the pyridine compound 23 since we observed that upon treatment of 12 with HBF4 in acetone, even at -78 °C, only decomposition of the starting material occurs. Attempts to perform substitution reactions of the hydroxo complexes 11 and 12 in methanol as the solvent led to a noteworthy result. After dissolving 11 or 12 in CH3OH at room temperature, in a relatively short period of time a change of color from orange or green to pale brown took place, and, after removal of the solvent and crystallization of the residue from pentane, the carbonyl(dihydro)iridium(III) compounds 24 and 25 (see Scheme 5) were isolated in, respectively, 88% and 91% yield. Apart from the strong ν(CO) stretching mode at 1978 cm-1 (24) and 1972 cm-1 (25) in the IR spectra, the most typical spectroscopic features of the octahedral complexes are both the hydride resonance at δ -9.27 (24) and -9.47 (25) and the signal for the CHdCdC proton at δ 6.53 (24) and 6.31 (25) in the 1H NMR spectra. The chemical shift of the latter is in good agreement with that of other allenyl transition-metal complexes.21 Since the NMR spectra display only one single resonance for the Ir-H protons, which is split into a sharp doublet of triplets due to P,H and H,H couplings, and only one signal for the two phosphorus atoms, there is no doubt that the two hydrides as well as the two PiPr3 ligands are in trans disposition. If the reaction of 11 is carried out in CD3OD instead of CH3OH, the tris(deuterio) compound [IrD2(CDdCd CPh2)(CO)(PiPr3)2] (24-d3) is formed, the 1H NMR spectrum of which does not exhibit a signal around δ (20) (a) Selegue, J. P. Organometallics 1982, 1, 217-218. (b) Bruce, M. I. Chem. Rev. 1991, 91, 197-257. (c) Le Bozec, H.; Dixneuf, P. H. Russ. Chem. Bull. 1995, 44, 801-812. (d) Werner, H. Chem. Commun. 1997, 903-910. (e) Bruce, M. I. Chem. Rev. 1998, 98, 2797-2858. (f) Cadierno, V.; Gamasa, M. P.; Gimeno, J. Eur. J. Inorg. Chem. 2001, 571-591. (21) (a) Elsevier: C. J.; Kleijn, H.; Boersma, J.; Vermeer, P. Organometallics 1986, 5, 716-720. (b) Keng, R.-S.; Lin, Y.-C. Organometallics 1990, 9, 289-291. (c) Shuchart, C. E.; Willis, R. R.; Wojcicki, A. J. Organomet. Chem. 1992, 424, 185-198. (d) Werner, H.; Flu¨gel, R.; Windmu¨ller, B.; Michenfelder, A.; Wolf, J. Organometallics 1995, 14, 612-618.

3788


Figure 4. VT

31P

Ilg and Werner

NMR spectrum of compound 27 (in toluene-d8). Scheme 6

6.5 or in the high-field region. It should be mentioned that there is ample precedence for the generation of a (carbonyl)hydrido complex from a chloro, bromo, or iodo metal precursor and a primary alcohol (or its anion) and that it is generally assumed that (aldehyde)(hydrido)metal intermediates are involved in this fragmentation process.22,23 The nearest analogy to the formation of 24 and 25 from 11 and 12, we are aware of, is the preparation of [IrH2(CO)(CHdCHPh)(PiPr3)2] from (22) (a) Vaska, L.; Diluzio, J. W. J. Am. Chem. Soc. 1961, 83, 12621263. (b) Vaska, L. J. Am. Chem. Soc. 1964, 86, 1943-1950. (c) Gill, D. F.; Shaw, B. L. Inorg. Chim. Acta 1979, 32, 19-23. (23) (a) Esteruelas, M. A.; Werner, H. J. Organomet. Chem. 1986, 303, 221-231. (b) Werner, H.; Esteruelas, M. A.; Meyer, U.; Wrackmeyer, B. Chem. Ber. 1987, 120, 11-15. (c) Stahl, S.; Werner, H. J. Am. Chem. Soc. 1991, 113, 2944-2947.

trans-[IrCl(dCdCHPh)(PiPr3)2] and NaOCH3, which affords the vinyl compound in excellent yield.24 A New Type of Alkyne Insertion into a CarbonIridium Bond. The observation that the (hydroxo)vinylidene complex trans-[Ir(OH)(dCdCHPh)(PiPr3)2] reacts with phenylacetylene and methylpropiolate by elimination of water to give the alkynyl derivatives trans-[Ir(CtCR)(dCdCHPh)(PiPr3)2]5 prompted us to study also the reactivity of 11 and 12 toward terminal alkynes. Stirring a solution of 11 or 12 in benzene with a 10-fold excess of the alkyne for 30 min at room temperature leads to a change of color from orange to violet or red and, after chromatographic workup and (24) Ho¨hn A.; Werner, H. J. Organomet. Chem. 1990, 382, 255272.



recrystallization from pentane, affords the novel iridium(III) complexes 26-29 in 87-92% isolated yield (Scheme 6). The elemental analyses as well as the spectroscopic data of the compounds indicated that not only a substitution of the OH group for a CtCR unit but also the coordination of a second alkynyl ligand plus the generation of a highly unsaturated C5 moiety had taken place. The supposed stereochemistry of the products formed by alkyne insertion has been substantiated by the X-ray crystal structure analysis of 26 (Figure 3). The coordination geometry around the metal center is squarepyramidal with two trans-disposed alkynyls and two trans-disposed phosphines in the basal plane and the σ-bonded allenylvinyl unit in the apical position. The bond angles of the two axes, P1-Ir-P2 (167.77(6)°) and C40-Ir-C50 (172.4(3)°), deviate somewhat from the ideal value of 180°, which is possibly due to the steric requirements of the C5 ligand. The Ir-C1 bond lies not exactly perpendicular to the basal plane of the pyramide but is slightly bent toward the carbon atom C50. The distance Ir-C1 (1.998(6) Å) is marginally shorter than the Ir-C40 and Ir-C50 bond lengths (2.020(6) and 2.018(6) Å) but virtually identical to the Ir-C distance in the six-coordinate (vinyl)iridium(III) complex [IrHCl(CHdCH2)(NCMe)(PiPr3)2] (1.99(2) Å).25 The carboncarbon bond lengths C1-C2, C3-C4, and C4-C5 (1.35(1), 1.32(1), and 1.31(1) Å) are significantly shorter than the distance C2-C3 (1.46(1) Å), which confirms the presence of an allenylvinyl ligand. The 31P NMR data of compounds 26-29 deserve some comment. While the spectra of 26, 28, and 29 display at room temperature the expected single resonance, indicating the equivalence of the two phosphine ligands, the spectrum of 27 shows two slightly broadened singlets in close proximity. They probably represent the two central lines of an AB system. At lower temperatures, the two signals sharpen (Figure 4), whereas by increasing the temperature from 293 to 313 K (when decomposition begins to occur) the lines broaden and would presumably coalesce at around 320-330 K. Although we have not done a reliable VT NMR study for 29 (and therefore cannot make any conclusion about the nonrigidity of this compound), we assume that the observed temperature dependence of the 31P NMR spectrum of 27 is due to the linkage of two different substituents at the terminal carbon atom of the C5 chain. Provided that the rotation around the C-C single bond of the allenylvinyl ligand is slow on the NMR time scale, the two phosphines are stereochemically nonequivalent and thus two separate signals should appear. In contrast to 26, the 1H and 13C NMR spectra of 27 also display two resonances for the PCH and the PCH nuclei of the isopropyl groups, which supports our assumption about the different environment at the sites of the PiPr3 ligands. With regard to the mechanism of formation of the complexes 26-29, the most remarkable feature is that despite the strength of the metal-carbon double bond in the starting materials 11 and 12 a coupling of an alkyne molecule with the C3 fragment occurs under exceedingly mild conditions. It is conceivable that the

The work presented in this paper illustrates that the (allenylidene)iridium(I) complexes of general composition trans-[IrCl{dCdCdC(Ph)R}(PiPr3)2] (3, 4) offer a rich chemistry indeed. The chloro ligand can be substituted not only by other halides but also by relatives thereof such as OCN-, SCN-, or N3- and even by OH-. The noteworthy message is that besides 3 and 4 the corresponding hydroxo compounds trans-[Ir(OH){dCd CdC(Ph)R}(PiPr3)2] (11, 12) can equally be used as starting materials to incorporate anionic O-donor, Ndonor, and C-donor ligands into the coordination sphere of iridium. The azido (13, 14) and phenolato (19) complexes react with carbon monoxide by migratory insertion of the allenylidene unit into the Ir-N and Ir-O bonds, thus generating functionalized alkynyl ligands. While the insertion product trans-[Ir{CtCCPh(N3)R}(CO)(PiPr3)2] with R ) tBu (16) is quite inert, the analogous compound with R ) Ph (15) reacts under mild conditions by elimination of N2 to afford the cyanosubstituted (vinyl)iridium(I) complex 17. The hydroxo derivatives 11 and 12 not only undergo acid-base reactions with PhOH, CF3CO2H, NEt3‚3HF, and [pyH]-

(25) Werner, H.; Ortmann, D. A.; Ilg, K. Z. Anorg. Allg. Chem. 2000, 626, 2457-2462.

(26) Wiedemann, R.; Steinert, P.; Gevert, O.; Werner, H. J. Am. Chem. Soc. 1996, 118, 2495-2496.

insertion reaction is preceded first by the substitution of OH for CtCR′ followed by the generation of the (hydrido)iridium(III) intermediate [IrH(CtCR′)2{dCd CdC(Ph)R}(PiPr3)2], which then rearranges to an allenyl unit that undergoes the C-C coupling process. It should be mentioned that in contrast to 11 the related compound trans-[RhCl(dCdCdCPh2)(PiPr3)2] reacts with phenylacetylene to give, via coupling of the C3 moiety with the alkyne and one of the phosphines, a rhodium(I) complex containing the unusual Wittig-type ylide iPr3PdCH-C(Ph)dCdCdCPh2 as a neutral π-bonded ligand.26 The reaction of 11 with PhCtCD affords the bis(deuterio) derivative 26-d2, the 1H NMR spectrum of which does not exhibit a signal for the IrCH or the CHd CdCPh2 proton. From this we conclude that the OH unit (or the eliminated water molecule) is not involved in the formation of the allenylvinyl ligand. In the presence of carbon monoxide, compounds 26 and 27 do not react by insertion of CO into the Ir-CH bond. Instead, addition of CO to the metal center occurs, and the octahedral (carbonyl)iridium(III) complexes 30 and 31 are formed in excellent yields. Both compounds are significantly more stable in solution than the coordinatively unsaturated precursors 26 and 27. In complete analogy with 27, the 31P NMR spectrum of 31 (but not that of 30) displays two signals at δ -4.0 and -4.2, which confirms that the two phosphine ligands are stereochemically not exactly equivalent. Moreover, the 13C NMR spectrum of 31 exhibits two resonances for the Ir-CtC carbon atoms at δ 86.5 and 80.9, indicating that in contrast to 27 also the two alkynyl groups are different. We assume that due to the increase of the coordination number from five to six the rotation around the metal-vinyl bond is somewhat hindered, and thus a different stereochemical environment of the ligands lying in the basal plane of the octahedron results. Conclusions

3790


BF4 but also react with methanol by complete fragmentation of the OCH3 moiety to give the six-coordinate (allenyl)(carbonyl)dihydridoiridium(III) compounds 24 and 25. An unusual insertion process, for which to the best of our knowledge there is no precedence, takes place upon treatment of the hydroxo complexes 11 and 12 with phenylacetylene and methylpropiolate leading via C-C coupling to a novel σ-bonded C5 unit. Although some mechanistic details of the reactions of 11 and 12 with various substrates are still unresolved, the results summarized in Schemes 4, 5, and 6 supplement recent discoveries by Milstein27 and Bergman,28 which showed that both (hydroxo)- and (alkoxo)iridium(III)snot iridium(I)scompounds are valuable starting materials for carrying out substitution, elimination, and insertion reaction. Experimental Section All reactions were carried out under an atmosphere of argon by Schlenk techniques. The starting materials 1,29 4,2 and HCtCCPh(tBu)OH30 were prepared as described in the literature. NMR spectra were recorded on Bruker AC 200 and Bruker AMX 400 instruments at room temperature. IR spectra were recorded on a Bruker IFS 25 FT-IR and mass spectra on a Finnigan MAT 90 (70 eV) or on a Hewlett-Packard G 1800 GCD instrument. Melting points were measured by DTA. The term vt indicates a virtual triplet, and N ) 3J(P,H) + 5J(P,H) or 1J(P,C) + 3J(P,C). Preparation of [IrHCl{CtCCPh(tBu)OH}(PiPr3)2] (2). A solution of 1 (170 mg, 0.31 mmol) in 20 mL of hexane was treated at -20 °C with HCtCCPh(tBu)OH (58 mg, 0.31 mmol), which led to a rapid evolution of gas (H2) and to a change of color from orange-yellow to red. After the reaction mixture was warmed to room temperature, it was stirred for 10 min and then concentrated to ca. 5 mL in vacuo. A red solid precipitated, the crystallization of which was completed by storing the solution at -78 °C. The solid was separated from the mother liquor, washed with small amounts of pentane (0 °C), and dried in vacuo: yield 192 mg (84%); mp 42 °C. Anal. Calcd for C31H58ClIrOP2: C, 50.56; H, 7.94. Found: C, 50.10; H, 7.81. IR (C6H6): ν(OH) 3481, ν(IrH) 2300, ν(CtC) 2092 cm-1. 1H NMR (C6D6, 200 MHz): δ 7.90, 7.24 (both m, 5 H, C6H5), 3.11 (m, 6 H, PCHCH3), 1.20 [br m, 45 H, PCHCH3 and C(CH3)3], -42.44 [t, J(P,H) ) 11.6 Hz, 1 H, Ir-H]. 13C NMR (C6D6, 50.3 MHz): δ 146.2 (s, ipso-C of C6H5), 128.5, 128.3, 126.6, 126.4 (all s, C6H5), 115.6 (s, Ir-CtC), 80.7 [t, J(P,C) ) 16.3 Hz, IrCtC], 74.0 (s, COH), 39.9 [s, C(CH3)3], 26.3 [s, C(CH3)3], 25.4 (vt, N ) 26.4 Hz, PCHCH3), 20.5 (s, PCHCH3). 31P NMR (C6D6, 162.0 MHz): δ 37.8 (s). Preparation of trans-[IrCl{dCdCdC(Ph)tBu}(PiPr3)2] (3). A solution of 2 (200 mg, 0.27 mmol) in 10 mL of ether was treated with 4 µL of CF3CO2H and stirred for 3 h at room temperature. The solvent was evaporated in vacuo, the residue was dissolved in 3 mL of acetone, and the solution was stored for 18 h at -78 °C. A red-violet solid precipitated, which was separated from the mother liquor, washed with small amounts of pentane (0 °C), and dried in vacuo: yield 178 mg (91%); mp 154 °C. Anal. Calcd for C31H56ClIrP2: C, 51.83; H, 7.86. (27) (a) Blum, O.; Milstein, D. Angew. Chem. 1995, 107, 210-212; Angew. Chem., Int. Ed. Engl. 1995, 34, 229-231. (b) Blum, O.; Milstein, D. J. Am. Chem. Soc. 1995, 117, 4582-4594. (28) (a) Woerpel, K. A.; Bergman, R. G. J. Am. Chem. Soc. 1993, 115, 7888-7889. (b) Ritter, J. C. M.; Bergman, R. G. J. Am. Chem. Soc. 1997, 119, 2580-2581. (c) Ritter, J. C. M.; Bergman, R. G. J. Am. Chem. Soc. 1998, 120, 6826-6827. (29) (a) Hietkamp, S.; Stufkens, D. J.; Vrieze, K. J. Organomet. Chem. 1978, 152, 347-357. (b) Werner, H.; Wolf, J.; Ho¨hn, A. J. Organomet. Chem. 1985, 287, 395-407. (30) Strzelecki, L.; Maric, B. Bull. Soc. Chim. Fr. 1969, 12, 4413.

Ilg and Werner Found: C, 51.99; H, 7.73. MS (70 eV): m/z 718 (M+ for 193Ir). IR (C6H6): ν(CdCdC) 1890 cm-1. 1H NMR (C6D6, 200 MHz): δ 7.16, 7.04, 6.83 (all m, 5 H, C6H5), 2.88 (m, 6 H, PCHCH3), 1.27 [dvt, N ) 13.5, J(H,H) ) 7.3 Hz, 36 H, PCHCH3], 1.06 [s, 9 H, C(CH3)3]. 13C NMR (C6D6, 100.6 MHz): δ 237.8 [t, J(P,C) ) 3.7 Hz, IrdCdCdC], 215.6 [t, J(P,C) ) 13.4 Hz, IrdCdCd C], 162.7 (s, ipso-C of C6H5), 152.8 (s, IrdCdCdC), 126.5, 126.2, 115.6 (all s, C6H5), 57.2 [s, C(CH3)3], 22.9 (vt, N ) 26.9 Hz, PCHCH3), 22.5 [s, C(CH3)3], 20.0 (s, PCHCH3). 31P NMR (C6D6, 162.0 MHz): δ 22.4 (s). Preparation of trans-[IrBr(dCdCdCPh2)PiPr3)2] (5). A solution of 4 (52 mg, 0.07 mmol) in 15 mL of acetone was treated with NaBr (35 mg, 0.35 mmol) and stirred for 6 h at room temperature. The solvent was evaporated, the residue was extracted with 30 mL of benzene/pentane (1:5), and the extract was brought to dryness in vacuo. The residue was dissolved in 3 mL of acetone, and the solution was stored for 12 h at -78 °C. Dark red crystals precipitated, which were separated from the mother liquor, washed twice with 1 mL of pentane (0 °C), and dried: yield 46 mg (83%); mp 152 °C dec. Anal. Calcd for C33H52BrIrP2: C, 50.63; H, 6.70. Found: C, 50.51; H, 6.71. IR (C6H6): ν(CdCdC) 1866 cm-1. 1H NMR (C6D6, 200 MHz): δ 7.99, 7.59, 6.71 (all s, 10 H, C6H5), 3.13 (m, 6 H, PCHCH3), 1.33 [dvt, N ) 13.4, J(H,H) ) 7.3 Hz, 36 H, PCHCH3]. 13C NMR (C6D6, 50.3 MHz): δ 249.8 [t, J(P,C) ) 3.8 Hz, IrdCdCdC], 193.9 [t, J(P,C) ) 14.0 Hz, IrdCdCdC], 162.8 [t, J(P,C) ) 1.9 Hz, ipso-C of C6H5], 140.0 [t, J(P,C) ) 1.9 Hz, IrdCdCdC], 130.0, 126.6, 121.1 (all s, C6H5), 23.7 (vt, N ) 26.8 Hz, PCHCH3), 20.3 (s, PCHCH3). 31P NMR (C6D6, 81.0 MHz): δ 16.4 (s). Preparation of trans-[IrI(dCdCdCPh2)(PiPr3)2] (6). A solution of 4 (65 mg, 0.09 mmol) in 15 mL of acetone was treated with KI (150 mg, 0.90 mmol) and stirred for 3 h at room temperature. The solvent was evaporated, the residue was extracted with 50 mL of pentane, and the extract was brought to dryness in vacuo. The residue was dissolved in 2 mL of acetone, and the solution was stored for 12 h at -78 °C. Violet crystals precipitated, which were separated from the mother liquor, washed twice with 1 mL of pentane (0 °C), and dried: yield 64 mg (88%); mp 78 °C dec. Anal. Calcd for C33H52IIrP2: C, 47.77; H, 6.32. Found: C, 47.42; H, 6.21. IR (KBr): ν(CdCdC) 1879 cm-1. 1H NMR (C6D6, 200 MHz): δ 8.02, 7.59, 6.70 (all s, 10 H, C6H5), 3.27 (m, 6 H, PCHCH3), 1.33 [dvt, N ) 13.5, J(H,H) ) 6.7 Hz, 36 H, PCHCH3]. 13C NMR (C6D6, 50.3 MHz): δ 248.1 [t, J(P,C) ) 4.2 Hz, IrdCdCdC], 186.2 [t, J(P,C) ) 14.0 Hz, IrdCdCdC], 163.3 (s, ipso-C of C6H5), 141.4 [t, J(P,C) ) 2.4 Hz, IrdCdCdC], 130.1, 126.6, 120.7 (all s, C6H5), 24.8 (vt, N ) 26.8 Hz, PCHCH3), 20.5 (s, PCHCH3). 31P NMR (C6D6, 81.0 MHz): δ 13.1 (s). Preparation of trans-[Ir(NCO)(dCdCdCPh2)(PiPr3)2] (7). This compound was prepared as described for 6 from 4 (60 mg, 0.08 mmol) and NaOCN (55 mg, 0.80 mmol) in 15 mL of acetone. Dark red solid: yield 53 mg (88%); mp 147 °C dec. Anal. Calcd for C34H52IrONP2: C, 54.82; H, 7.04; N, 1.88. Found: 54.61; H, 6.93; N, 1.77. IR (KBr): ν(OCN)as 2228, ν(Cd CdC) 1882, ν(OCN)sym 1448 cm-1. 1H NMR (C6D6, 400 MHz): δ 7.96, 7.58, 6.71 (all s, 10 H, C6H5), 2.76 (m, 6 H, PCHCH3), 1.23 [dvt, N ) 13.8, J(H,H) ) 7.3 Hz, 36 H, PCHCH3]. 13C NMR (C6D6, 100.6 MHz): δ 250.5 [t, J(P,C) ) 3.1 Hz, IrdCd CdC], 212.5 [t, J(P,C) ) 14.1 Hz, IrdCdCdC], 162.1 (s, ipso-C of C6H5), 147.0 (m, NCO), 137.8 [t, J(P,C) ) 2.0 Hz, IrdCd CdC], 130.1, 130.0, 126.6 (all s, C6H5), 23.8 (vt, N ) 25.4 Hz, PCHCH3), 20.0 (s, PCHCH3). 31P NMR (C6D6, 162.0 MHz): δ 20.7 (s). Preparation of trans-[Ir(NCO){dCdCdC(Ph)tBu}(PiPr3)2] (8). This compound was prepared as described for 6 from 3 (64 mg, 0.09 mmol) and NaOCN (59 mg, 0.09 mmol) in 15 mL of acetone. Dark red solid: yield 62 mg (95%); mp 147 °C dec. Anal. Calcd for C32H56IrNOP2: C, 53.02; H, 7.79; N, 1.93. Found: C, 53.32; H, 7.58; N, 1.81. IR (CH2Cl2): ν(OCN)as 2229, ν(CdCdC) 1895, ν(OCN)sym 1458 cm-1. 1H NMR (C6D6,

Square-Planar Allenylidene Ir Complexes 200 MHz): δ 7.11, 7.03, 6.81 (all m, 5 H, C6H5), 2.58 (m, 6 H, PCHCH3), 1.18 [dvt, N ) 14.0 Hz, J(H,H) ) 7.0 Hz, 36 H, PCHCH3], 1.03 [s, 9 H, C(CH3)]. 13C NMR (C6D6, 50.3 MHz): δ 237.7 [t, J(P,C) ) 3.7 Hz, IrdCdCdC], 228.9 [t, J(P,C) ) 14.0 Hz, IrdCdCdC], 162.4 (s, ipso-C of C6H5), 152.3 [t, J(P,C) ) 2.4 Hz, IrdCdCdC], 145.5 (m, NCO), 126.6, 126.2, 115.8 (all s, C6H5), 56.6 [s, C(CH3)3], 23.5 (vt, N ) 26.8 Hz, PCHCH3), 22.6 [s, C(CH3)3], 19.8 (s, PCHCH3). 31P NMR (C6D6, 81.0 MHz): δ 24.5 (s). Preparation of trans-[Ir(NCS)(dCdCdCPh2)(PiPr3)2] (9). This compound was prepared as described for 6 from 4 (74 mg, 0.10 mmol) and KSCN (97 mg, 1.00 mmol) in 15 mL of acetone. Dark red solid: yield 65 mg (86%); mp 84 °C. Anal. Calcd for C34H52IrNP2S: C, 53.66; H, 6.89; N, 1.85; S, 4.21. Found: C, 53.40; H, 6.80; N, 1.76; S, 4.00. IR (CH2Cl2): ν(SCN)as 2077, ν(CdCdC) 1886, ν(SCN)sym 1463 cm-1. 1H NMR (C6D6, 400 MHz): δ 7.94, 7.57, 6.90 (all m, 10 H, C6H5), 2.74 (m, 6 H, PCHCH3), 1.23 [dvt, N ) 13.8, J(H,H) ) 7.0 Hz, 36 H, PCHCH3]. 13C NMR (C6D6, 100.6 MHz): δ 246.3 [t, J(P,C) ) 3.6 Hz, IrdCdCdC], 217.6 [t, J(P,C) ) 13.2 Hz, IrdCdCd C], 163.2 (s, NCS), 163.1 (s, ipso-C of C6H5), 140.5 [t, J(P,C) ) 2.5 Hz, IrdCdCdC], 130.1, 127.0, 122.0 (all s, C6H5), 24.1 (vt, N ) 26.7 Hz, PCHCH3), 20.0 (s, PCHCH3). 31P NMR (C6D6, 162.0 MHz): δ 22.3 (s). Preparation of trans-[Ir(NCS){dCdCdC(Ph)tBu}(PiPr3)2] (10). This compound was prepared as described for 6 from 3 (61 mg, 0.08 mmol) and KSCN (78 mg, 0.80 mmol) in 15 mL of acetone; reaction time 4 h. Red solid: yield 56 mg (90%); mp 151 °C dec. Anal. Calcd for C32H56IrNP2S: C, 51.87; H, 7.62; N, 1.89; S, 4.33. Found: C, 52.02; H, 7.48; N, 1.77; S, 4.43. IR (CH2Cl2): ν(SCN)as 2080, ν(CdCdC) 1901, ν(SCN)sym 1462 cm-1. 1H NMR (C6D6, 200 MHz): δ 7.06, 6.78 (both m, 5 H, C6H5), 2.54 (m, 6 H, PCHCH3), 1.17 [dvt, N ) 13.5, J(H,H) ) 6.8 Hz, 36 H, PCHCH3], 1.00 [s, 9 H, C(CH3)3]. 13C NMR (C6D6, 100.6 MHz): δ 235.0 [t, J(P,C) ) 3.0 Hz, IrdCdCdC], 234.6 [t, J(P,C) ) 12.2 Hz, IrdCdCdC], 161.7 [t, J(P,C) ) 2.4 Hz, IrdCdCdC], 161.9 (s, ipso-C of C6H5), 156.0 (s, SCN), 126.7, 126.4, 115.9 (all s, C6H5), 56.5 [s, C(CH3)3], 23.9 (vt, N ) 25.6 Hz, PCHCH3), 22.7 [s, C(CH3)3], 19.8 (s, PCHCH3). 31P NMR (C6D6, 81.0 MHz): δ 25.3 (s). Preparation of trans-[Ir(OH)(dCdCdCPh2)(PiPr3)2] (11). A solution of 4 (70 mg, 0.09 mmol) in 20 mL of acetone was treated with KOH (34 mg, 0.60 mmol) and stirred for 2 h at room temperature. A change of color from red to orange was observed. The solvent was evaporated in vacuo, the residue was extracted with 50 mL of pentane, and the solution was concentrated to ca. 3 mL in vacuo. After the solution was stored for 12 h at -78 °C, orange crystals precipitated, which were separated from the mother liquor, washed with small amounts of pentane (0 °C), and dried: yield 54 mg (84%); mp 104 °C dec. Anal. Calcd for C33H53IrOP2: C, 55.05; H, 7.42. Found: C, 55.53; H, 7.57. IR (C6H6): ν(OH) 3643 ν(CdCdC) 1857 cm-1. 1H NMR (C6D6, 400 MHz): δ 8.10, 7.60, 6.79 (all m, 10 H, C6H5), 4.25 (br s, 1 H, OH), 2.80 (m, 6 H, PCHCH3), 1.31 [dvt, N ) 13.5, J(H,H) ) 7.3 Hz, 36 H, PCHCH3]. 13C NMR (C6D6, 100.6 MHz): δ 252.8 [t, J(P,C) ) 3.1 Hz, IrdCd CdC], 202.7 [t, J(P,C) ) 12.7 Hz, IrdCdCdC], 161.9 [t, J(P,C) ) 2.5 Hz, ipso-C of C6H5], 129.8, 125.5, 121.8 (all s, C6H5), 22.6 (vt, N ) 24.4 Hz, PCHCH3), 20.0 (s, PCHCH3); signal of Ird CdCdC not exactly located. 31P NMR (C6D6, 162.0 MHz): δ 23.5 (s). Preparation of trans-[Ir(OH){dCdCdC(Ph)tBu}(PiPr3)2] (12). This compound was prepared as described for 11 from 3 (80 mg, 0.11 mmol) and KOH (34 mg, 0.60 mmol) in 20 mL of acetone; reaction time 3 h. Green solid: yield 58 mg (75%); mp 63 °C dec. Anal. Calcd for C31H57IrOP2: C, 53.19; H, 8.21. Found: C, 53.12; H, 8.27. IR (C6H6): ν(OH) 3480, ν(Cd CdC) 1869 cm-1. 1H NMR (C6D6, 200 MHz): δ 7.25, 7.02, 6.88 (all m, 5 H, C6H5), 3.80 (br s, 1 H, OH), 2.62 (m, 6 H, PCHCH3), 1.26 [dvt, N ) 13.5, J(H,H) ) 6.8 Hz, 36 H, PCHCH3], 1.13 [s, 9 H, C(CH3)]. 13C NMR (C6D6, 50.3 MHz): δ 239.1 [t, J(P,C) )

Organometallics, Vol. 20, No. 17, 2001 3791 3.7 Hz, IrdCdCdC], 217.4 [t, J(P,C) ) 12.8 Hz, IrdCdCdC], 162.0 (s, ipso-C of C6H5), 138.7 [t, J(P,C) ) 2.4 Hz, IrdCd C)C], 126.5, 125.6, 117.0 (all s, C6H5), 54.9 [s, C(CH3)3], 23.1 [s, C(CH3)3], 22.2 (vt, N ) 25.6 Hz, PCHCH3), 19.9 (s, PCHCH3). 31P NMR (C6D6, 81.0 MHz): δ 27.1 (s). Preparation of trans-[Ir(N3)(dCdCdCPh2)(PiPr3)2] (13). This compound was prepared as described for 6 from 4 (74 mg, 0.10 mmol) and NaN3 (33 mg, 0.50 mmol) in 15 mL of acetone. Deep red solid: yield 68 mg (91%); mp 114 °C dec. Anal. Calcd for C33H52IrN3P2: C, 53.21; H, 7.04; N, 5.64. Found: C, 52.93; H, 6.71; N, 5.48. MS (70 eV): m/z 745 (M+ for 193Ir), 717 [M+ - N2], 703 [M+ - N3]. IR (hexane): ν(N3) 2066, ν(CdCdC) 1870 cm-1. 1H NMR (C6D6, 400 MHz): δ 7.97, 7.57, 6.72 (all m, 10 H, C6H5), 2.78 (m, 6 H, PCHCH3), 1.26 [dvt, N ) 13.5, J(H,H) ) 7.0 Hz, 36 H, PCHCH3]. 13C NMR (C6D6, 100.6 MHz): δ 248.3 [t, J(P,C) ) 3.1 Hz, IrdCdCdC], 206.4 [t, J(P,C) ) 13.7 Hz, IrdCdCdC], 161.9 (br s, ipso-C of C6H5), 136.0 (br s, IrdCdCdC), 130.0, 126.5, 121.7 (all s, C6H5), 24.0 (vt, N ) 25.8 Hz, PCHCH3), 19.9 (s, PCHCH3). 31P NMR (C6D6, 162.0 MHz): δ 23.5 (s). Preparation of trans-[Ir(N3){dCdCdC(Ph)tBu}(PiPr3)2] (14). This compound was prepared as described for 6 from 3 (45 mg, 0.06 mmol) and NaN3 (40 mg, 0.60 mmol) in 15 mL of acetone; reaction time 1.5 h. Orange solid: yield 43 mg (95%); mp 98 °C dec. Anal. Calcd for C31H56IrN3P2: C, 51.34; H, 7.79; N, 5.80. Found: C, 51.71; H, 7.61; N, 5.93. IR (CH2Cl2): ν(N3) 2078, ν(CdCdC) 1895 cm-1. 1H NMR (C6D6, 200 MHz): δ 7.02, 6.82 (both m, 5 H, C6H5), 2.61 (m, 6 H, PCHCH3), 1.21 [dvt, N ) 13.5, J(H,H) ) 6.8 Hz, 36 H, PCHCH3], 1.05 [s, 9 H, C(CH3)3]. 13C NMR (C6D6, 50.3 MHz): δ 235.8 [t, J(P,C) ) 4.9 Hz, IrdCdCdC], 222.8 [t, J(P,C) ) 14.0 Hz, IrdCdCdC], 162.1 (s, ipso-C of C6H5), 150.8 (s, IrdCdCdC), 126.6, 126.2, 116.0 (all s, C6H5), 52.6 [s, C(CH3)3], 23.7 (vt, N ) 25.6 Hz, PCHCH3), 22.7 [s, C(CH3)3], 19.7 (s, PCHCH3). 31P NMR (C6D6, 81.0 MHz): δ 27.0 (s). Preparation of trans-[Ir{C≡CC(N3)Ph2}(CO)(PiPr3)2] (15). A slow stream of CO was passed through a solution of 13 (72 mg, 0.10 mmol) in 10 mL of acetone for 15 s at -78 °C. When the solution was warmed to room temperature, a change of color from deep red to orange-yellow occurred. The solution was stirred for 5 min at 20 °C, concentrated to ca. 2 mL in vacuo, and then stored for 24 h at -78 °C. Yellow crystals precipitated, which were separated from the mother liquor, washed with small amounts of acetone (-20 °C), and dried: yield 62 mg (83%); mp 86 °C dec. Anal. Calcd for C34H52IrN3OP2: C, 52.83; H, 6.78; N, 5.44. Found: C, 52.38; H, 7.00; N, 5.29. IR (hexane): ν(N3) 2098, ν(CO) 1933 cm-1. 1H NMR (C6D6, 400 MHz): δ 7.67, 7.16, 7.06 (all m, 10 H, C6H5), 2.59 (m, 6 H, PCHCH3), 1.24 [dvt, N ) 13.5, J(H,H) ) 7.0 Hz, 36 H, PCHCH3]. 13C NMR (C6D6, 100.6 MHz): δ 188.0 [t, J(P,C) ) 10.2 Hz, Ir-CO], 144.4 (s, ipso-C of C6H5), 130.8, 128.7, 127.8 (all s, C6H5), 127.4 [t, J(P,C) ) 4.1 Hz, Ir-CtC-C], 115.0 (br s, Ir-CtC-C), 71.7 (s, Ir-CtC-C), 25.6 (vt, N ) 27.7 Hz, PCHCH3), 19.8 (s, PCHCH3). 31P NMR (C6D6, 162.0 MHz): δ 42.4 (s). Preparation of trans-[Ir{CtCCPh(N3)tBu}(CO)(PiPr3)2] (16). This compound was prepared as described for 15 from 14 (40 mg, 0.06 mmol) and CO in 10 mL of acetone. Yellow solid: yield 39 mg (90%); mp 76 °C dec. Anal. Calcd for C32H56IrN3OP2: C, 51.04; H, 5.70; N, 5.58. Found: C, 50.78; H, 5.40; N, 5.76. IR (C6H6): ν(N3) 2104, ν(CtC) 2050, ν(CO) 1932 cm-1. 1H NMR (C D , 200 MHz): δ 7.72, 7.11 (both m, 5 H, C H ), 6 6 6 5 2.70 (m, 6 H, PCHCH3), 1.29 [dvt, N ) 13.9, J(H,H) ) 7.3 Hz, 18 H, PCHCH3], 1.27 [dvt, N ) 13.2, J(H,H) ) 6.6 Hz, 18 H, PCHCH3], 1.11 [s, 9 H, C(CH3)3]. 13C NMR (C6D6, 50.3 MHz): δ 187.0 [t, J(P,C) ) 11.0 Hz, Ir-CO], 141.1 (s, ipso-C of C6H5), 129.0, 128.3, 127.1 (all s, C6H5), 124.4 [t, J(P,C) ) 15.8 Hz, Ir-CtC], 114.9 (s, Ir-CtC), 77.5 (s, Ir-CtC-C), 41.0 [s, C(CH3)3], 26.3 [s, C(CH3)3], 26.0 (vt, N ) 26.9 Hz, PCHCH3), 20.1, 20.0 (both s, PCHCH3). 31P NMR (C6D6, 81.0 MHz): δ 42.3 (s).

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Preparation of trans-[Ir{η1-C(CN)dCPh2}(CO)(PiPr3)2] (17). A solution of 15 (50 mg, 0.06 mmol) in 1 mL of benzene was stirred for 24 h at room temperature. The solvent was evaporated in vacuo, the residue was dissolved in 2 mL of acetone, and the solution was stored for 15 h at -78 °C. Yellow crystals precipitated, which were separated from the mother liquor, washed with small amounts of acetone (0 °C), and dried: yield 43 mg (90%); mp 161 °C dec. Anal. Calcd for C34H52IrNOP2: C,54.82; H, 7.04; N, 1.88. Found: C, 54.71; H, 7.14; N, 1.75. IR (C6H6): ν(CN) 2159, ν(CO) 1937 cm-1. 1H NMR (C6D6, 400 MHz): δ 8.64, 7.40, 7.35, 7.13 (all m, 10 H, C6H5), 2.42 (m, 6 H, PCHCH3), 1.30 [dvt, N ) 14.2, J(H,H) ) 7.3 Hz, 18 H, PCHCH3], 1.03 [dvt, N ) 13.5, J(H,H) ) 7.0 Hz, 18 H, PCHCH3]. 13C NMR (C6D6, 100 MHz): δ 186.0 [t, J(P,C) ) 11.1 Hz, Ir-CO], 161.3 [t, J(P,C) ) 5.1 Hz, Ir-C(CN)dC], 146.3, 143.4 (both s, ipso-C of C6H5), 142.4 [t, J(P,C) ) 12.7 Hz, Ir-C(CN)dC], 130.8, 129.3, 128.7, 128.3, 127.4, 127.1 (all s, C6H5), 125.9 [t, J(P,C) ) 2.0 Hz, Ir-C(CN)dC], 26.5 (vt, N ) 27.5 Hz, PCHCH3), 20.5, 19.5 (both s, PCHCH3). 31P NMR (C6D6, 162.0 MHz): δ 32.7 (s). Preparation of trans-[Ir(OPh)(dCdCdCPh2)(PiPr3)2] (18). A solution of 11 (57 mg, 0.08 mmol) in 10 mL of benzene was treated with phenol (7.5 mg, 0.08 mmol) and stirred for 5 min at room temperature. A rapid change of color from orange to red occurred. The solvent was evaporated in vacuo, and the residue extracted with 25 mL of acetone. After the extract was concentrated to ca. 2 mL and then stored for 20 h at -78 °C, dark red crystals precipitated. They were separated from the mother liquor, washed twice with small quantities of pentane (-20 °C), and dried: yield 49 mg (82%); mp 86 °C dec. Anal. Calcd for C39H57IrOP2: C, 58.84; H, 7.22. Found: C, 58.63; H, 7.45. IR (C6H6): ν(CdCdC) 1868 cm-1. 1H NMR (C6D6, 100.6 MHz): δ 7.98, 7.57, 7.28, 6.78, 6.65, 6.43 (all m, 15 H, C6H5), 2.60 (m, 6 H, PCHCH3), 1.25 [dvt, N ) 13.2, J(H,H) ) 7.0 Hz, 36 H, PCHCH3]. 13C NMR (C6D6, 100.6 MHz): δ 255.7 [t, J(P,C) ) 3.6 Hz, IrdCdCdC], 203.6 [t, J(P,C) ) 13.7 Hz, Ird CdCdC], 169.3 (s, ipso-C of OC6H5), 162.7 [t, J(P,C) ) 2.0 Hz, ipso-C of C6H5), 131.8 [t, J(P,C) ) 3.1 Hz, IrdCdCdC], 129.7, 128.9, 126.2, 121.8, 121.7, 115.4 (all s, C6H5), 23.8 (vt, N ) 25.8 Hz, PCHCH3), 20.2 (s, PCHCH3). 31P NMR (C6D6, 162.0 MHz): δ 23.3 (s). Preparation of trans-[Ir(OPh){dCdCdC(Ph)tBu}(PiPr3)2] (19). This compound was prepared as described for 18 from 12 (40 mg, 0.06 mmol) and phenol (5.4 mg, 0.06 mmol) in 10 mL of benzene. Brown solid: yield 41 mg (89%); mp 131 °C. Anal. Calcd for C37H61IrOP2: C, 57.26; H, 7.92. Found: C, 57.43; H, 7.80. IR (C6H6): ν(CdCdC) 1875 cm-1. 1H NMR (C6D6, 200 MHz): δ 7.26, 7.17, 7.03, 6.86, 6.65, 6.48 (all m, 10 H, C6H5), 2.44 (m, 6 H, PCHCH3), 1.20 [dvt, N ) 13.4, J(H,H) ) 6.7 Hz, 36 H, PCHCH3], 1.10 [s, 9 H, C(CH3)3]. 13C NMR (C6D6, 50.3 MHz): δ 240.8 [t, J(P,C) ) 3.7 Hz, IrdCdCdC], 219.3 [t, J(P,C) ) 13.4 Hz, IrdCdCdC], 169.1 (s, ipso-C of OC6H5), 163.0 [t, J(P,C) ) 2.4 Hz, IrdCdCdC], 146.5 (s, ipso-C of C6H5), 129.7, 126.5, 126.0, 121.3, 116.5, 115.0 (all s, C6H5), 56.4 [s, C(CH3)3], 23.4 (vt, N ) 24.4 Hz, PCHCH3), 23.0 [s, C(CH3)3], 20.0 (s, PCHCH3). 31P NMR (C6D6, 162.0 MHz): δ 27.2 (s). Preparation of trans-[Ir{CtCCPh(OPh)tBu}(CO)(PiPr3)2] (20). A slow stream of CO was passed through a solution of 19 (45 mg, 0.06 mmol) in 10 mL of pentane for 30 s at -78 °C. After the solution was warmed to room temperature, the solvent was evaporated in vacuo, the residue was dissolved in 2 mL of acetone, and the solution was stored for 18 h at -78 °C. Yellow crystals precipitated, which were separated from the mother liquor, washed with small quantities of pentane (-20 °C), and dried: yield 39 mg (83%); mp 157 °C. Anal. Calcd for C38H61IrO2P2: C, 56.76; H, 7.65. Found: C, 56.51; H, 7.69. MS (70 eV): m/z 804 (M+ for 193Ir), 711 (M+ - OC6H5). IR (C6H6): ν(CO) 1930 cm-1. 1H NMR (C6D6, 400 MHz): δ 7.65, 7.10, 7.05, 6.96, 6.67 (all m, 10 H, C6H5), 2.67 (m, 6 H, PCHCH3), 1.30 [s, 9 H, C(CH3)3], 1.27, 1.22 [both

Ilg and Werner dvt, N ) 13.8, J(H,H) ) 6.8 Hz, 18 H each, PCHCH3]. 13C NMR (C6D6, 100.6 MHz): δ 186.8 [t, J(P,C) ) 11.2 Hz, Ir-CO], 157.1 (s, ipso-C of C6H5), 141.0 (s, ipso-C of OC6H5), 129.5, 128.6, 128.3, 126.9, 119.6, 118.6 (all s, C6H5), 125.4 [t, J(P,C) ) 15.7 Hz, Ir-CtC], 115.2 (s, Ir-CtC), 86.6 (s, Ir-CtC-C), 41.8 [s, C(CH3)3], 26.5 [s, C(CH3)3], 26.2 (vt, N ) 27.5 Hz, PCHCH3), 20.3, 20.2 (both s, PCHCH3). 31P NMR (C6D6, 162.0 MHz): δ 42.1 (s). Preparation of trans-[Ir(K1-O2CCF3){dCdCdC(Ph)tBu}(PiPr3)2] (21). A solution of 12 (60 mg, 0.08 mmol) in 10 mL of benzene was treated dropwise with a solution of CF3CO2H (6.6 µL, 0.08 mmol) in 1 mL of benzene at room temperature. A rapid change of color from green to red-violet occurred. After the solution was stirred for 5 min at 20 °C and then for 20 min at 40 °C, the solvent was evaporated in vacuo. The oily residue was dissolved in 2 mL of acetone, and the solution was stored for 12 h at -78 °C. Red-violet crystals precipitated, which were separated from the mother liquor, washed with small amounts of pentane (0 °C), and dried: yield 62 mg (91%); mp 106 °C. Anal. Calcd for C33H56IrO3P2: C, 49.80; H, 7.09. Found: C, 49.49; H, 6.90. IR (KBr): ν(CdCdC) 1902, ν(OCO)as 1709, ν(OCO)sym 1457 cm-1. 1H NMR (C6D6, 200 MHz): δ 7.04, 6.79 (both m, 5 H, C6H5), 2.45 (m, 6 H, PCHCH3), 1.21 [dvt, N ) 13.5, J(H,H) ) 6.8 Hz, 36 H, PCHCH3], 1.01 [s, 9 H, C(CH3)3]. 13C NMR (C6D6, 50.3 MHz): δ 235.8 [t, J(P,C) ) 3.7 Hz, IrdCdCdC], 224.9 [t, J(P,C) ) 13.4 Hz, IrdCdCdC], 161.8 [t, J(P,C) ) 2.4 Hz, IrdCdCdC], 160.0 [q, J(P,C) ) 36.0 Hz, CO2CF3], 156.1 (br s, ipso-C of C6H5), 128.3, 126.6, 116.0 (all s, C6H5), 117.7 [q, J(F,C) ) 291.1 Hz, CO2CF3], 56.7 [s, C(CH3)3], 23.7 (vt, N ) 25.6 Hz, PCHCH3), 22.8 [s, C(CH3)3], 19.9 (s, PCHCH3). 19F NMR (C6D6, 188.0 MHz): δ -74.5 (s). 31P NMR (C D , 81.0 MHz): δ 26.8 (s). 6 6 Preparation of trans-[IrF(dCdCdCPh2)(PiPr3)2] (22). A solution of 11 (69 mg, 0.10 mmol) in 10 mL of benzene was treated with NEt3‚3HF (5.2 µL, 0.10 mmol) and stirred for 3 min at room temperature. The solvent was evaporated in vacuo, and the residue was extracted with 50 mL of pentane. The extract was brought to dryness in vacuo, the residue was dissolved in 3 mL of acetone, and the solution was stored for 24 h at -78 °C. Red crystals precipitated, which were separated from the mother liquor, washed with small amounts of pentane (0 °C), and dried: yield 61 mg (88%); mp 89 °C dec. Anal. Calcd for C33H52FIrP2: C, 54.90; H, 7.26. Found: C, 55.09; H, 7.11. IR (CH2Cl2): ν(CdCdC) 1872 cm-1. 1H NMR (C6D6, 400 MHz): δ 8.03. 7.60, 6.76 (all m, 10 H, C6H5), 2.81 (m, 6 H, PCHCH3), 1.33 [dvt, N ) 13.5, J(H,H) ) 7.0 Hz, 36 H, PCHCH3]. 13C NMR (C6D6, 100.6 MHz): δ 259.1 (m, Ird CdCdC), 210.0 (m, IrdCdCdC), 163.0 (s, ipso-C of C6H5), 129.9, 126.1, 122.0 (all s, C6H5), 127.3 (m, IrdCdCdC), 23.1 (vt, N ) 25.4 Hz, PCHCH3), 20.1 (s, PCHCH3). 19F NMR (C6D6, 188.0 MHz): δ -145.3 [t, J(P,F) ) 20.0 Hz]. 31P NMR (C6D6, 162.0 MHz): δ 26.2 [d, J(F,P) ) 20.3 Hz]. Preparation of trans-[Ir(py){dCdCdC(Ph)tBu}(PiPr3)2]BF4 (23). A solution of 12 (70 mg, 0.10 mmol) in 10 mL of acetone was treated at -78 °C with [pyH]BF4 (17 mg, 0.10 mmol), which led to a change of color from green to red-violet. After the solution was warmed to room temperature, the solvent was evaporated in vacuo, and the residue was suspended in 30 mL of pentane. The suspension was irradiated in an ultrasonic bath for 10 min, which led to the formation of a red-violet solid. This was separated from the mother liquor and dried: yield 79 mg (93%); mp 38 °C dec. Anal. Calcd for C36H61BF4IrNP2: C, 50.94; H, 7.24; N, 1.65. Found: C, 51.21; H, 7.01; N, 1.58. Λ(CH3NO2): 64 cm2 Ω-1 mol-1. IR (CH2Cl2): ν(CdCdC) 1909 cm-1. 1H NMR (acetone-d6, 200 MHz): δ 8.21, 8.04, 7.88 (all m, 5 H, NC5H5), 7.44-7.23 (m, 5 H, C6H5), 2.18 (m, 6 H, PCHCH3), 1.20 [dvt, N ) 14.6, J(H,H) ) 7.3 Hz, 36 H, PCHCH3]. 13C NMR (acetone-d6, 100.6 MHz): δ 248.4 [t, J(P,C) ) 14.0 Hz, IrdCdCdC], 228.6 [t, J(P,C) ) 3.7 Hz, Ird CdCdC], 159.5 (s, ipso-C of C6H5), 127.8, 127.1, 126.9, 117.0, 116.7 (all s, C6H5 and NC5H5), 116.8 [t, J(P,C) ) 3.0 Hz, Ird

Square-Planar Allenylidene Ir Complexes CdCdC], 56.7 [s, C(CH3)3], 24.7 (vt, N ) 26.9 Hz, PCHCH3), 23.1 [s, C(CH3)3], 19.6 (s, PCHCH3). 31P NMR (acetone-d6, 81.0 MHz): δ 21.6 (s). 19F NMR (acetone-d6, 188.0 MHz): δ -150.7 (s). Preparation of [IrH2(CHdCdCPh2)(CO)(PiPr3)2] (24). A solution of 11 (55 mg, 0.08 mmol) in 10 mL of methanol was stirred for 30 min at room temperature. The solvent was evaporated in vacuo, and the residue was suspended in 40 mL of pentane. After the suspension was irradiated for 10 min in an ultrasonic bath, a pale yellow solid was formed, which was separated from the mother liquor and dried: yield 51 mg (88%); mp 28 °C dec. Anal. Calcd for C34H54IrOP2: C, 55.67; H, 7.42. Found: C, 55.89; H. 7.38. IR (KBr): ν(IrH) 2209, ν(CO) 1978, ν(CdCdC) 1885 cm-1. 1H NMR (C6D6, 200 MHz): δ 7.53, 7.13 (both m, 10 H, C6H5), 6.54 (m, 1 H, HCdCdC), 2.14 (m, 6 H, PCHCH3), 1.13 [dvt, N ) 13.5, J(H,H) ) 6.8 Hz, 36 H, PCHCH3], -9.27 [dt, J(P,H) ) 13.6, J(H,H) ) 3.4 Hz, 2 H, Ir-H]. 13C NMR (C6D6, 50.3 MHz): δ 208.1 [t, J(P,C) ) 3.0 Hz, HCdCdC], 176.1 [t, J(P,C) ) 9.7 Hz, Ir-CO], 141.3, 132.1 (both s, ipso-C of C6H5), 130.1, 129.9, 129.3, 126.6, 125.4, 121.5 (all s, C6H5), 98.9 (s, HCdCdC), 63.4 [t, J(P,C) ) 11.0 Hz, HCd CdC], 24.5 (vt, N ) 29.3 Hz, PCHCH3), 19.0 (s, PCHCH3). 31P NMR (C6D6, 81.0 MHz): δ 32.8 (s). Preparation of [IrD2(CDdCdCPh2)(CO)(PiPr3)2] (24d3). This compound was prepared as described for 24 (50 mg, 0.07 mmol) from 11 and 5 mL of CD3OD. Pale yellow solid: yield 44 mg (86%). 1H NMR (C6D6, 200 MHz): δ 7.68, 7.52, 7.09 (all m, 10 H, C6H5), 2.12 (m, 6 H, PCHCH3), 1.13 [dvt, N ) 13.1, J(H,H) ) 7.3 Hz, 36 H, PCHCH3]. 31P NMR (C6D6, 81.0 MHz): δ 32.8 (s). Preparation of [IrH2{CHdCdC(Ph)tBu}(CO)(PiPr3)2] (25). This compound was prepared as described for 24 from 12 (80 mg, 0.11 mmol) and 10 mL of methanol. Pale yellow solid: yield 75 mg (91%): mp 72 °C dec. Anal. Calcd for C32H59IrOP2: C, 53.83; H, 8.33. Found: C, 54.08; H, 8.11. IR (KBr): ν(IrH) 2053, ν(CO) 1972, ν(CdCdC) 1764 cm-1. 1H NMR (C6D6, 400 MHz): δ 7.27, 7.12, 7.02 (all m, 5 H, C6H5), 6.31 (m, 1 H, HCdCdC), 2.16 (m, 6 H, PCHCH3), 1.30 [s, 9 H, C(CH3)3], 1.18, 1.09 [both dvt, N ) 13.7, J(H,H) ) 7.6 Hz, 18 H, PCHCH3], -9.47 [dt, J(P,H) ) 13.8, J(H,H) ) 4.6 Hz, 2 H, Ir-H]. 13C NMR (C6D6, 100.6 MHz): δ 207.5 [t, J(P,C) ) 3.0 Hz, HCd CdC], 176.5 [t, J(P,C) ) 9.2 Hz, Ir-CO], 142.0 (s, ipso-C of C6H5), 130.4, 127.6, 125.0 (all s, C6H5), 102.7 (s, HCdCdC), 63.3 [t, J(P,C) ) 11.2 Hz, HCdCdC], 50.8 [s, C(CH3)3], 31.7 [s, C(CH3)3], 24.5 (vt, N ) 29.3 Hz, PCHCH3), 19.0 (s, PCHCH3). 31P NMR (C6D6, 81.0 MHz): δ 33.0 (s). Preparation of [Ir(CtCPh)2{η1-(E)-CHdCPhCHdCd CPh2}(PiPr3)2] (26). A solution of 11 (55 mg, 0.08 mmol) in 10 mL of benzene was treated with an excess of phenylacetylene (81 µL, 0.80 mmol) and stirred for 30 min at room temperature. A change of color from orange to deep violet occurred. The solvent was evaporated in vacuo, the residue was dissolved in 1 mL of benzene, and the solution was chromatographed on Al2O3 (neutral, acitivity grade V, height of column 5 cm). With pentane, a violet fraction was eluted, which was brought to dryness in vacuo. Recrystallization from pentane at -78 °C gave violet crystals, which were separated from the mother liquor and dried: yield 70 mg (87%); mp 53 °C. Anal. Calcd for C57H69IrP2: C, 67.90; H, 6.90. Found: C, 68.01; H, 7.04. IR (C6H6): ν(C≡C) 2078, 2076 cm-1. 1H NMR (C6D6, 400 MHz): δ 9.36 (s, 1 H, HCdCdC), 7.93 (br s, 1 H, IrCH), 7.63, 7.46, 7.34, 7.23, 7.15-6.93, 6.74 (all m, 25 H, C6H5), 3.27 (m, 6 H, PCHCH3), 1.32 [dvt, N ) 13.2, J(H,H) ) 6.6 Hz, 18 H, PCHCH3], 1.27 [dvt, N ) 13.2, J(H,H) ) 7.0 Hz, 18 H, PCHCH3]. 13C NMR (C6D6, 100.6 MHz): δ 211.6 (s, HCd CdC), 177.3 [t, J(P,C) ) 4.0 Hz, Ir-CHdC], 153.3, 148.5, 143.5, 138.4 (all s, ipso-C of C6H5), 132.9, 132.6, 131.3, 130.4, 128.8, 128.6, 128.4, 128.3, 127.9, 127.6, 126.8, 126.1 (all s, C6H5), 119.3 [t, J(P,C) ) 12.2 Hz, Ir-CtCPh], 115.3 [t, J(P,C) ) 4.1 Hz, Ir-CtCPh], 111.4 (s, HCdCdC), 104.5 [t, J(P,C) ) 8.1 Hz, IrCH], 100.9 (s, HCdCdC), 24.6 (vt, N ) 26.4 Hz,

Organometallics, Vol. 20, No. 17, 2001 3793 PCHCH3), 20.4, 20.2 (both s, PCHCH3). 31P NMR (C6D6, 162.0 MHz): δ 13.0 (s). Preparation of [Ir(CtCPh)2{η1-(E)-CDdCPhCDdCd CPh2}(PiPr3)2] (26-d2). This compound was prepared as described for 26 from 11 (42 mg, 0.06 mmol) and excess PhCt CD (60 µL, 0.60 mmol). Violet solid: yield 51 mg (85%). 1H NMR (C6D6, 200 MHz): δ 7.70, (all m, 25 H, C6H5), 3.26 (m, 6 H, PCHCH3), 1.29 (m, 36 H, PCHCH3). 31P NMR (C6D6, 81.0 MHz): δ 13.5 (s). Preparation of [Ir(CtCPh)2{η1-(E)-CHdCPhCHdCd C(Ph)tBu}(PiPr3)2] (27). This compound was prepared as described for 26 from 12 (38 mg, 0.05 mmol) and excess phenylacetylene (50 µL, 0.50 mmol). Violet solid: yield 48 mg (91%); mp 121 °C dec. Anal. Calcd for C55H73IrP2: C, 66.84; H, 7.44. Found: C, 66.59; H, 7.54. IR (KBr): ν(CtC) 2084, 2071, ν(CdCdC) 1874 cm-1. 1H NMR (C6D6, 200 MHz): δ 8.80 (s, 1 H, HCdCdC), 7.52 (br s, 1 H, IrCH), 7.66, 7.44, 7.21, 7.05 (all m, 2 OH, C6H5), 3.26, 3.17 (both m, 3 H each, PCHCH3), 1.31, 1.17 (both m, 18 H each, PCHCH3), 1.09 [s, 9 H, C(CH3)3]. 13C NMR (C6D6, 100.6 MHz): δ 211.8 (s, HCd CdC), 144.9, 139.4 (both s, ipso-C of C6H5), 133.9 [t, J(P,C) ) 4.1 Hz, Ir-CHdC], 128. 3, 128.0, 127.8, 127.1, 125.9, 125.1, 122.6 (all s, C6H5), 115.8 (s, Ir-CtC), 101.1 [t, J(P,C) ) 8.1 Hz, IrCH], 99.3 (s, HCdCdC), 97.4 (s, HCdCdC), 53.3 [s, C(CH3)3], 30.1 [s, C(CH3)3], 24.3, 22.6 (both m, PCHCH3), 20.0, 19.8 (both s, PCHCH3), signal of IrCtC not exactly located. 31P NMR (C D , 81.0 MHz): δ 13.0, 12.9 (both s). 6 6 Preparation of [Ir(CtCCO2Me)2{η1-(E)-CHdC(CO2Me)CHdCPh2}(PiPr3)2] (28). This compound was prepared as described for 26 from 10 (57 mg, 0.08 mmol) and excess methylpropiolate (50 µL, 0.80 mmol). Red-orange solid: yield 71 mg (89%); mp 62 °C dec. Anal. Calcd for C45H63IrO6P2: C, 56.65; H, 6.66. Found: C, 56.95; H, 6.51. IR (C6H6): ν(CtC) 2084, ν(OCO)as ) 1686, ν(OCO)sym ) 1431 cm-1. 1H NMR (C6D6, 400 MHz): δ 9.40 (s, 1 H, HCdCdC), 8.63 (br s, 1 H, IrCH), 7.80, 7.24, 7.11 (all m, 10 H, C6H5), 3.41 (s, 6 H, CO2CH3), 3.33 (s, 3 H, CO2CH3), 3.11 (m, 6 H, PCHCH3), 1.13 [dvt, N ) 14.0, J(H,H) ) 7.1 Hz, 36 H, PCHCH3]. 13C NMR (C6D6, 100.6 MHz): δ 211.4 (s, HCdCdC), 162.8, 154.5 (both s, CO2CH3), 138.7 (s, ipso-C of C6H5), 129.5, 128.5, 126.8 (all s, C6H5), 126.4 [t, J(P,C) ) 4.1 Hz, Ir-CtC], 123.5 [t, J(P,C) ) 7.1 Hz, IrCHdC], 111.4 (s, HCdCdC), 94.2 (s, HCdCdC), 51.4, 51.3 (both s, CO2CH3), 25.1 (vt, N ) 27.3 Hz, PCHCH3), 19.9 (s, PCHCH3), signals for Ir-CHdC and Ir-CtC not exactly located. 31P NMR (C6D6, 162.0 MHz): δ 16.9 (s). Preparation of [Ir(CtCCO2Me)2{η1-(E)-CHdC(CO2Me)CHdCdC(Ph)tBu}(PiPr3)2] (29). This compound was prepared as described for 26 from 12 (34 mg, 0.05 mmol) and excess methylpropiolate (60 µL, 0.67 mmol). Red-orange solid: yield 42 mg (92%); mp 98 °C. Anal. Calcd for C43H67IrO6P2: C, 55.29; H, 7.23. Found: C, 54.97; H, 7.21. IR (KBr): ν(CtC) 2081, ν(OCO)as ) 1684, ν(OCO)sym ) 1457 cm-1. 1H NMR (C6D6, 400 MHz): δ 9.02 (s, 1 H, HCdCdC), 8.11 (br s, 1 H, IrCH), 7.57, 7.22, 7.13 (all m, 5 H, C6H5), 3.43 (br s, 9 H, CO2CH3), 3.08 (m, 6 H, PCHCH3), 1.39 [s, 9 H, C(CH3)3], 1.13 (m, 36 H, PCHCH3). 13C NMR (CD2Cl2, 50.3 MHz): δ 206.2 (s, HCdCdC), 163.6, 154.6 (both s, CO2CH3), 138.9 (s, ipso-C of C6H5), 129.7, 128.6, 127.7 (all s, C6H5), 126.7 [t, J(P,C) ) 3.7 Hz, Ir-CHdC], 126.1 (br s, Ir-CHdC), 121.6 [t, J(P,C) ) 4.2 Hz, Ir-CtC], 119.9 (br s, Ir-CtC), 114.3 (s, HCdCdC), 91.8 (s, HCdCdC), 66.4 [s, C(CH3)3], 51.9, 51.4 (both s, CO2CH3), 30.1 [s, C(CH3)3], 25.0 (vt, N ) 26.8 Hz, PCHCH3), 19.9, 19.8 (both s, PCHCH3). 31P NMR (C6D6, 162.0 MHz): δ 16.3 (s). Preparation of [Ir(CtCPh)2{η1-(E)-CHdCPhCHdCd CPh2}(CO)(PiPr3)2] (30). A slow stream of CO was passed through a solution of 26 (30 mg, 0.03 mmol) in 5 mL of benzene for 15 s at room temperature. A change of color from violet to light yellow occurred. After the solution was stirred for 5 min, the solvent was evaporated in vacuo. The oily residue was dissolved in 1 mL of pentane and the solution stored for 6 h at -78 °C. A pale yellow solid precipitated, which was

3794


separated from the mother liquor and dried: yield 28 mg (93%); mp 136 °C dec. Anal. Calcd for C58H69IrOP2: C, 67.22; H, 6.71. Found: C, 67.53; H, 6.66. IR (CH2Cl2): ν(C≡C) 2114, ν(CO) 2031, ν(CdCdC) 1936 cm-1. 1H NMR (C6D6, 200 MHz): δ 9.51 (s, 1 H, HCdCdC), 8.15 [t, J(P,H) ) 3.5 Hz, 1 H, IrCH], 7.65, 7.42, 7.0 (all m, 25 H, C6H5), 2.89 (m, 6 H, PCHCH3), 1.42 [dvt, N ) 14.3, J(H,H) ) 6.0 Hz, 18 H, PCHCH3], 1.27 [dvt, N ) 13.5, J(H,H) ) 6.6 Hz, 18 H, PCHCH3]. 13C NMR (C6D6, 50.3 MHz): δ 210.6 (s, HCdCdC), 172.0 [t, J(P,C) ) 12.7 Hz, Ir-CO], 147.7 (s, ipso-C of C6H5), 142.7 [t, J(P,C) ) 3.6 Hz, Ir-CHdC], 135.4 [t, J(P,C) ) 12 Hz, Ir-CHdC], 132.0, 131.1, 131.0, 129.5, 129.4, 126.7, 125.9, 125.6, 125.5 (all s, C6H5), 112.6 (s, Ir-CtC), 110.9 (s, HCdCdC), 107.4 (s, IrCtC), 101.9 (s, HCdCdC), 86.4 [t, J(P,C) ) 12.2 Hz, Ir-Ct C], 80.4 [t, J(P,C) ) 11.0 Hz, Ir-CtC], 24.9 (vt, N ) 28.0 Hz, PCHCH3), 20.2, 19.6 (both s, PCHCH3). 31P NMR (C6D6, 81.0 MHz): δ -3.8 (s). Preparation of [Ir(CtCPh)2{η1-(E)-CHdCPhCHdCdC(Ph)tBu}(CO)(PiPr3)2] (31). This compound was prepared as described for 30 from 27 (50 mg, 0.05 mmol) and CO in 10 mL of benzene/pentane (1:1). Pale yellow solid: yield 47 mg (92%); mp 136 °C dec. Anal. Calcd for C56H73IrOP2: C, 66.81; H, 7.24. Found: C, 67.53; H, 6.66. MS (70 eV): m/z 1017 (M+). IR (CH2Cl2): ν(CtC) 2115, ν(CO) 2027, ν(CdCdC) 1928 cm-1. 1H NMR (C D , 200 MHz): δ 8.97 (s, 1 H, HCdCdC), 7.78 [t, 6 6 J(P,H) ) 2.9 Hz, IrCH], 7.64, 7.50, 7.39-7.19, 7.10-6.94 (all m, 20 H, C6H5), 2.94, 2.74 (both m, 3 H each, PCHCH3), 1.30 [dvt, N ) 13.5, J(H,H) ) 6.6 Hz, 36 H, PCHCH3], 1.13 [s, 9 H, C(CH3)3]. 13C NMR (C6D6, 50.3 MHz): δ 205.0 (s, HCdCdC), 171.8 [t, J(P,C) ) 7.3 Hz, Ir-CO], 148.7 (s, ipso-C of C6H5), 143.9 [t, J(P,C) ) 3.7 Hz, Ir-CHdC], 131.1, 131.0, 130.0, 129.6, 126.4, 125.7, 125.5, 125.4 (all s, C6H5), 115.5 (s, HCd CdC), 112.4, 107.3, 100.3 (all s, Ir-CtC and HCdCdC), 86.5 [t, J(P,C) ) 12.2 Hz, Ir-CtC], 80.9 [t, J(P,C) ) 11.0 Hz, IrCtC], 67.9 [s, C(CH3)3], 34.8 [s, C(CH3)3], 24.9 (m, PCHCH3), 20.3, 20.2 (both s, PCHCH3). 31P NMR (C6D6, 81.0 MHz): δ -4.0, -4.2 (both s).

Ilg and Werner X-ray Structural Determination of Compounds 4, 22, and 26. Single crystals of 4 were grown by cooling a solution in ether to -60 °C, those of 22 by cooling a solution in acetone to -60 °C, and those of 26 by cooling a solution in ether to 5 °C. The data were collected on an Enraf-Nonius CAD4 diffractometer using monochromated Mo KR radiation (λ ) 0.71073 Å). Crystal data were corrected by Lorentz and polarization effects, and empirical absorption corrections were applied (Ψ-scan method, minimum transmission 61.25% (4), 90% (22), 84.03% (26)). The structures were solved by direct methods (SHELXS-97).31 Atomic coordinates and anisotropic thermal parameters of non-hydrogen atoms were refined by full-matrix least squares on F2 (SHELXL-97).32 The positions of all hydrogen atoms were calculated according to ideal geometry and refined using the riding method.

Acknowledgment. We thank the Deutsche Forschungsgemeinschaft (Grant SFB 347) and the Fonds der Chemischen Industrie for financial support, the latter in particular for a Ph.D. Grant to K.I. Moreover, we gratefully acknowledge support by Mrs. R. Schedl and Mr. C. P. Kneis (elemental analyses and DTA), Mrs. M.-L. Scha¨fer and Dr. W. Buchner (NMR measurements), BASF AG for various gifts of chemicals, and in particular Mr. S. Stellwag for practical assistance. Supporting Information Available: Tables of crystal data and refinement parameters, bond lengths and angles, and positional and thermal parameters for 4, 22, and 26. This material is available free of charge via the Internet at http://pubs.acs.org. OM010353M (31) Sheldrick, G. M. Acta Crystallogr. Sect. A 1990, 46, 467-473. (32) Sheldrick, G. M. SHELXL-97, Program for Crystal Structure Refinement; Universita¨t Go¨ttingen, 1997.

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